6230 security code

I have found a 6230 in a taxi last night. It was still on with about 25 missed calls on it.
He/she houldnt have been so careless as far as I am concerned, so I hope to keep it.

When i tried to take off the keylock it asked for a security code.
So turned off & lobbed the sim, put in my sim, entered my sim PIN, it came on ok and showed my operator etc, but the keylock is automatically on, I did menu-* and it asks for this security code again.
I tried my sims PIN again but wont take it so must be the phones internal security code it wants, tried the Nokia default 12345 but still nothing...

Can anyone tell me how I clear this off to use with my sim?
If I get a cable will I be able to do this then???
Cheers!

default security code is 12345 and u say that int workin so it mush have been changed then try formating mmc card dont do it in phone format it with a card reader sometimes when formated on phone the phone will not reconise the card